WARNING - THE NIJINO U-BOOT BOOTLOADER IS NOT FULLY TESTED. ALTHOUGH IT HAS BEEN INSTALLED SUCCESSFULLY ON BOTH STANDARD AND HG KURO BOXES, THERE HAS BEEN AT LEAST ONE KUROBOX BRICKED. THINK LONG AND HARD BEFORE PERFORMING THIS MODIFICATION. A BRICKED KURO REQUIRES JTAG ACCESS TO REPAIR AND IS NOT COVERED UNDER THE KUROBOX WARRANTY

Introduction

The U-Boot project for the Kurobox is something that the community was waiting for since a long time ! Nijino was the first one to provide a patch to adapt U-Boot to the Kurobox architecture and specifications !
It'll allow you to boot from a kernel on the hard drive, thing that was not possible since the buffalo's boot was only booting from the kernel in flash (that is a 2.4.17 kernel version).

Known functions and limitations

Functions :

Will boot a kernel image in uImage format stored on a HDD

Will boot in EM (Emergency Mode) if pressing red button at bootup just after the HDD light stop blinking (The EM mode take around 2 minutes to start for me, so don't worry if after few seconds you still can't ping your Kurobox)

Limitations :

This version of U-Boot comes with no support for ethernet, so for now booting or connecting to u-boot from network is impossible. According to the Nijino, the author of the patch, Ethernet driver implementation will not be easy, so we may never see this function in our Kuroboxes !

Building the Linux kernel in U-Boot format

To be able to build a kernel in uImage format, you'll need mkimage tool that is built when compiling U-Boot (check Building you own U-Boot binary section if you want to build it).
You can download a compiled version of this tool here. Just download it, chmod 0755 it and move the file to /usr/bin.
Now to compile the kernel, follow the usual way :

export ARCH=ppc
make menuconfig
make oldconfig

and then instead of the make vmlinux, do a

make uImage

it'll create a uImage file there : arch/ppc/boot/images/uImage, so after kernel compilation, do a

just get the file according to the Kurobox you have and "tar xzf" it from root (/)

Flash U-Boot in your Kurobox

!!!! Warning : this could brick your Kurobox in case of misuse/power failure/application crash !!!! Kurobox and Kurobox HG are not using the same boot, be carefull !!!!
!!!! Warning : this could brick your Kurobox in case of misuse/power failure/application crash !!!! Kurobox and Kurobox HG are not using the same boot, be carefull !!!!
!!!! Warning : this could brick your Kurobox in case of misuse/power failure/application crash !!!! Kurobox and Kurobox HG are not using the same boot, be carefull !!!!
!!!! Warning : this could brick your Kurobox in case of misuse/power failure/application crash !!!! Kurobox and Kurobox HG are not using the same boot, be carefull !!!!

I have built (using gcc version 4.1.2 20060613 (prerelease) (Debian 4.1.1-5)) both versions of patched U-Boot (1.1.4), both will try to boot the /boot/uImage on hda1.